With the rapid technological development in recent years, the luminous efficiency and the brightness of the light emitting diode is accepted by the public, so that the light emitting diode is used widely for example in backlight assembly, car lamp, and street light, etc. However, with the increasing brightness, the larger amount of heat emission from the light emitting diode has become a troublesome issue in the industry. If the heat emission cannot be removed efficiently, the brightness of the light emitting diode will be decreased and the corresponding service life will become shorter.
Please refer to FIG. 1. FIG. 1 shows a front view of a traditional LED device assembly 100. The conventional LED device assembly 100 is disposed on a circuit board 10. The LED device assembly 100 includes a light emitting diode 110, a substrate 120, a reflector 130, and an insulator 140. The substrate 120 is a MCPCB (Metal Core PCB) substrate. The light emitting diode 110 and the reflector 130 are both disposed on the substrate 120. The reflector 130 defines a cup-shaped cavity 132. The light emitting diode 110 is disposed in the cavity 132. The light emitting diode 110 is joined to the substrate 120 by a conductive paste 102. The side wall of the cavity 132 has a relatively smooth reflective surface and is able to reflect the light emitting from the light emitting diode 110, so that the directivity of the light is improved.
However, the reflector 130 and the substrate 120 are of two different elements, so that after an extended usage period, the reflector 130 may be dislocated or separated from the substrate 120. The heat emitted from the light emitting diode 110 is transferred to the outside environment via the substrate 120 and the circuit board 10; for this reason, the heat dissipation efficiency of the light emitting diode 110 is dependent on the thickness of the substrate 120. Therefore, the heat dissipation efficiency of the LED device assembly 100 is decreased as the thickness of the substrate 120 is increased. However, the mechanical strength of the LED device assembly 100 will be weakened if the thickness of the substrate becomes thinner. The conductive paste which can be used, can be for example such as a silver paste, and the silver paste includes polymer material and other materials having inferior thermal conductivity so that the heat emitted from the light emitting diode 110 cannot be dissipated efficiently. In recent years, a technical solution offered by replacing the silver paste with an eutectic structure, for example: Au—Sn eutectic structure, is provided. However, this technical solution has the disadvantages of added process complexity and higher cost.
Hence, there is a need in the art for improving the heat dissipation efficiency of the LED device assembly 100.